Brain Perfusion and Brain Diffusion

General Information | Scheduling, Insurance and Preparation | What to Expect


General information General Information

About Brain Perfusion and Brain Diffusion

CT perfusion image of the brain.

A brain perfusion scan is an imaging technique that is of great use when a stroke has occurred. Brain perfusion can be performed using either a CT scan or an MRI scan. Recent technological advances in these scanners have made it easy to image the brain in detail never before possible. By quickly detecting a stroke and identifying its cause, doctors can more rapidly take action to limit, and potentially reverse, its damaging effects.

With brain perfusion, images are quickly taken over a 60-75 second time frame to watch the circulation in the brain. Contrast medium is rapidly injected during the scan. It is the circulation of the contrast that is captured in the images. With CT perfusion, multi-slice CT scanners provide the speed needed to determine the extent of brain tissue that has been deprived of its blood supply during the first few hours after the onset of a stroke. With MR perfusion, an ultra-fast technique called echo-planar imaging, or EPI, is used to generate the images of the brain tissue and blood supply. With both techniques, a radiologist can quickly evaluate any areas where the blood supply has been disrupted or decreased due to the narrowing or blockage of arteries.

A brain diffusion scan is performed in an MRI scanner and also uses EPI. MR Brain diffusion utilizes the principle of microscopic water movement in the brain tissue. Under normal conditions, water in the brain tissue moves rather freely. When a disruption to the blood supply of the brain occurs, the tissue will swell. This swelling will decrease the freedom with which the water can move about. The restriction in movement is visible on the MR diffusion scan images.

MR brain diffusion done along with MR brain perfusion yields information about the amount of brain tissue that has suffered irreversible damage and also the amount of tissue that is "at risk" of irreversible damage, but may still be salvageable.

MR diffusion image of a brain suffering a stroke.

Brain perfusion and diffusion are often combined with cerebral angiography to provide a comprehensive picture of the circulatory activity in the brain. With this comprehensive picture, a radiologist can see not only the area of the brain affected by the blood flow disruption, but also in many cases, the cause of the disruption itself. A team of physicians can then determine the best course of treatment to minimize the effects of stroke.

Back to top.

Risks Involved in Brain Perfusion and Brain Diffusion

Following are some of the risks associated with brain perfusion and brain diffusion:

CT Brain Perfusion

  • Risk of radiation exposure; however, it is well below the level that generally causes adverse affects.
  • Risk of allergic reaction to the contrast material used during the procedure.
  • If you have impaired kidney function, there is the risk of your condition being aggravated by the contrast.

MR Brain Perfusion or Brain Diffusion

  • Risk of allergic reaction to the contrast material if used during the procedure.
  • Claustrophobic patients may be uncomfortable.
  • Undetected metal implants can be affected by the magnetic field or they can interfere with the readability of the images.

Back to top.


Scheduling, Insurance and Preparation Scheduling, Insurance and Preparation

Exam Locations

Brain perfusion and brain diffusion are emergency exams that are performed by Radiology Imaging Associates radiologists at the following Radiology Imaging Associates partner hospitals:

  • Medical Center of Aurora
  • Littleton Adventist Hospital
  • Porter Adventist Hospital
  • Sky Ridge Medical Center
  • Swedish Medical Center

Insurance Coverage

Emergency procedures are usually covered by insurance. Contact your insurance company to check your coverage for this procedure and emergency room visits.

Conditions to Let Us Know About

Brain perfusion and brain diffusion exams are often done in emergency situations. If it’s possible, in advance of your exam, let your Radiology Imaging Associates radiologist or technologist know if any of the following circumstances apply to you:

CT Brain Perfusion

  • Currently pregnant or nursing
  • Previous reaction to iodine or contrast material
  • Renal disease
  • Asthma with inhaler use 2 times or more per day
  • Diabetic

MR Brain Perfusion or Brain Diffusio

  • Currently pregnant or nursing
  • Dental fillings or braces
  • Currently have a metal plate, pins, screws, or staples in the skull
  • Previous reaction to MRI contrast medium (gadolinium)
  • Claustrophobia
  • Any magnetic, mechanical or electronic devices
  • brain aneurysm surgery or ear implants

Preparation Guidelines

There are no preparation guidelines for brain perfusion and brain diffusion since they are done under emergency circumstances.

Back to top.


What to Expect What to Expect

During the Exam

A patient enters the MRI scanner.

Here is generally what will happen during brain perfusion and brain diffusion exams:

CT Brain Perfusion

  1. A technologist will ask you some safety questions and answer your questions if possible.
  2. All metal and metallic objects, such as eyeglasses, belts, hair accessories and jewelry, will be removed.
  3. A small IV will be placed in your hand.
  4. The technologist will position you on the scanner table and your head will be moved into the machine.
  5. Contrast will be administered. You may feel a warm sensation as it enters your body or experience a metallic taste.
  6. During the scan, which typically lasts less than fifteen minutes, you will hear normal whirring and mechanical noises as the CT scanner rotates around your body. It is extremely important not to move any part of your body during the scan to avoid blurring the images.
  7. The IV will be removed after the exam is completed.

The technologist will not stay in the room during the scan, but you can speak with him or her throughout the exam by intercom.

MR Diffusion or Brain Perfusion

  1. A technologist will ask you some safety questions and answer your questions if possible.
  2. All metal and metallic objects, such as eyeglasses, belts, hair accessories and jewelry, will be removed.
  3. If contrast is needed, a small IV will be placed in your hand.
  4. The technologist will position you on the scanner table and your head will be moved into the machine.
  5. Contrast will be administered if needed. You may feel a warm or cool sensation as it enters your body.
  6. During the scan, which typically lasts less than thirty minutes, the MRI machine will make buzzing and banging sounds. You will be provided with earplugs or headphones to protect your hearing. It is extremely important not to move any part of your body during the MRI scan to avoid blurring the images.
  7. If an IV was needed, it will be removed after the exam is completed.

The technologist will not stay in the room during the scan, but you can speak with him or her throughout the exam by intercom.

Back to top.

After the Exam

Exam Results

A radiologist experienced in the interpretation of CT and MR physiologic brain studies will analyze the data and results from your exam. He reviews the images as soon as they are acquired and report the results immediately to the emergency room physician and members of the stroke alert team. This allows for the most appropriate course of treatment to begin as quickly as possible.

Print      A A A